Improvement in magnetic telegraphs



M. G. FARMER. Magnetic Telegraph,

No. 81,485. @Paten-tedA-ug 25,1888.

MOSES G. FARMER, OF SALEM, MASSACHUSETTS.

IIVIPROVMENT IN MAGNETIC TELEGRAPHS.

Specification forming part of Letters Patent No. SL48@ dated August 25, 1868.

-To all whomy it may concern:

sent simultaneously in opposite directions upon a single line or circuit of telegraph; and I do declare that the following description thereof is full and exact.

My improvement consists in so arranging, connecting, and combining a line of telegraph with a receiving-magnet, a rlicostat-key, and battery as to enable a person to send a inessage from one 'station to another, and to receive a message at the same time in return.

I will proceed to describe the construction of my invention.

Upon va suitable platform, F, Figure 1, I place a connnon receiving-magnet, M 5 also a suitable rheostat, R It', and a key, K E. These three elements-viz, the magnet M, rlieostat It R', and key K E-may be pla'ced upon separate stands, if desired. The key which I use is somewhat peculiar in its construction. The key-lever K E has two contact-points, B and O, to make contacts with two springs or levers, q g' and p p. One of these levers, q q', is connected by the wire r with the rhecstat .R It' at a. The other lever or spring, p p', is con'- nected at l', by the wire p", tothe receivingmagnet M. The other end, l, of. the wire of receiving-magnet M is connected, by the wire Z l", to the line screw-cup L.

The stationary part l`t ofthe rheostat is connected, by a Wire, n r, to the adjustable part r It of the rheostat, and this, in its turn, is connected, by the wire l" from a, to the linewlre screw-cup L. The construction of these various parts is fully shown in Figs. 1 and 2, while their mutual connection and dependence are more particularly evident from the skeleton sketch, Fig. 3. The up-and-down positions of the key KE are represented in Fig. 1.

To describe the action and illustrate the working of my invention, I will proceed as follows: Suppose the key K E at station 1 to be pressed down, the spring q will be lifted from .its rest w, the spring p p will be lifted from its anvil D, and both will be in the positlons represented. Both will be inv contact, at B and G, with the key K E, which is also in the position shown. The key K E is counected, by the wire g', to the screw-cup P, which receives a wire leading from one pole of a suitable battery, l? N, the other pole of the battery being connected with the ground. Now, the key .K E being pressed down, the current from the battery lJ N will pass, by the wire g', to the key at F. 4 Here it will di- `vide into two branches, one portion going, by the ccntactfB, lever q g', to the rheostat It at a; from iz., by i', r", It a, and Z, to the screwcup at L. The other portion of the current will go from. E, by the contact G, to the lever p 19'; by the wire p p, to the receivinganag-V net M at Z; from I., by the wires l and lf", to the line screw-cup L. Here both portions of the current imite, and, passing over the linewire, enter the receiving-magnet at station 2, as seen in Fig. 3, passing, by l', p, d, and wire g, to the ground at G, thereby completing the circuit aiulmoving the armature A of the receiving magnet M at station 2. In consequence of this action, the armature A of the receivin g-1nagnet M at. station 1 will be more or less attracted, according as the resistance of the rheostat R lt is more or Vless than the resistance of the receiving-magnet M. The tension of the armature-spring S may be so adjusted with reference to the relative resi stance of R It and Z M Z, that the armature A at station 1 shall notbe moved when its key i s pressed down, unless the key at station 2 is pressed down also. Shoulch however, the key at station 2 be now Ipressed down, the current from its battery N P will pass through its apparatus in a manner precisely similar to that described as taking place at station l.. The current on the line will now be that due to the action oi' both batteries, N I) and I3 N, (both acting in the same directio1i,) and the branch currents through the receiving-magnets M, at stations 1 and 2, will now bc stron ger than before, and, if the armature-springs S S are properly adjusted, the armature A A at each station will be set in motion, and attracted to their re spective magnets M M.

It' the key at either station (say, station 1) be now let up, the armature at the other station (station 2) will be retracted by its spring S, because there is not a current strong enen gli flowing through it to draw or keep the armature up tc the magnet, there being only the branch current g' E C p p Z M Z a iiowing through the magnet at station 2. When, however, these two branches at station 2 have united at u, and passed over the line and arrived at a, statioirl, the current does not fork here, because the key at station 1 is up. Consequently the rheostat branch of the circuit is open at I, and, of course, the whole of the current from station 2 will enter the receivingmagnet at station l, and pass, by Z, M, l', p, p', l), and g. to the ground G without passing through the batteryl? N at station l, its batterycircuit bei ng open at C p. Thus it will be seen that, when the key at station 1 is pressed down, it will work the armature at station 2, whether the key at station 2 be pressed or not. If it be pressed down, the current arriving at station l, added to the branch current at station 2, through its magnet M will move its armature A. If the key at station 2 be not pressed down, the current from station 1 will go wholly through the magnet at station 2, and will be strong enough to move its armature. So, in either ease, the armature at station 2 will answer to the Working of the key at station l, an d vice versa, the armature at station l will answer to the workin g of the key at station 2, whether the key at station l be up or down.

In general, I so adjust the rheostat that about halt' oi' the current Will, when the key is pressed down, be sent through the magnet M and the other half through the, rheostat R R', and. the armature-spring S should be so adjusted th at the armature will not move when its key is worked up and down, unless the other key is worked up and down also.

The rheostat lt R should be so constructed as to be able to offer, at pleasure, either considerably more or less resistance than is offered by the receiving-magnet M.

When the line is well insulated and in good working order, the rheostat at any station should be so adjusted as to otter about the same resistance as does the receiving-magnet.

It' the line be not so well insulated-*that is, if there be more or less escape upon the lineit will be necessary to alter the adjustment of the rheostat, and the proper adjustment is best found by Varying it while the key is being Worked up and down slowly, while the other station is working its key up and down more rapidly. The resistance of the rheostat and the tension of the armature-spring are thus varied while the keys are being thus Worked until the strokes ofthe armature, corresponding to the Working of the key at the other station, be of about equal loudness, whether the key be up or down.

This apparatus differs from that described in my Patent No. 26,097 in these respects:

In this apparatus there is a single set of coils upon the receiving-magnet. In that apparatus there was a double set of coils upon the receiving-magnet. In this apparatus the key makes two contacts at the downstroke, or, in other'words, closes two branch circuits- Viz, the branch through the receiving-magnet and the branch through the rheostat-both at the same time, and, at the same time, disconnecting the receiving-magnet from the direct ground and connecting it with the ground y through the battery. By the upstrokcs of the key, the reecivingdnagnet is disconnected from the battery and connected with the ground directly. The rheostat branch circuit is broken at the key at its upward stroke. In the other invention, the rheostat branch circuit was permanently connected with the receiving-magnet branch, side by side, or in multiple arc, and the rheostat branch circuit Was not broken from the receiving-magnet by the upward stroke of the key, as is done 'in this invention. In this apparatus the key is more complex and the receiving-magnet more simple than in the former invention.

Having thus described this my invention, I claim- The arrangement and combination of the rheostat receiving-magnet and two-point key or their equivalents, substantially as described.

MOSES G. FARMER.

Witnesses:

SAML. BATCHELDER, Jr., A. M. ALLEN. 

